Which of the following describes persistence in relation to pesticides?

Persistence in relation to pesticides refers to the duration that a pesticide remains active in the environment before breaking down or degrading. A pesticide with a long half-life that remains unchanged indicates that it does not easily break down, allowing it to remain effective for an extended period. This characteristic can raise concerns about environmental impact and potential accumulation in non-target organisms, ultimately affecting ecosystems and human health.

In contrast, the other options represent scenarios where the pesticide dissipates or breaks down quickly. A pesticide that rapidly breaks down (the first choice) would not be considered persistent, as it would have a short residence time in the environment. A biodegradable pesticide (the third choice) is one that can be broken down by natural processes, which implies low persistence. Furthermore, a pesticide that evaporates immediately (the fourth choice) would also not be persistent since it would not remain in the environment long enough to exert its effects. Therefore, the choice highlighting a pesticide with a long half-life that remains unchanged accurately captures the essence of persistence in pesticides.